N-3-substituted pyrimidinones as potent, orally active, AT1 selective angiotensin II receptor antagonists.

A novel series of nonpeptide angiotensin II (A II) antagonists containing a pyrimidinone ring which carries a C-linked biphenyltetrazole moiety and a carboxyheteroaryl group on the 3-position have been prepared. Their affinity for the AT1 receptor was determined in a binding assay on rat adrenal cortical membranes. The in vivo antihypertensive properties were tested by evaluating the inhibition of the pressor response to A II followed by iv and id administration. Extensive molecular modeling studies, including comparison of molecular electrostatic potential distributions, conformational analysis, and overlays on a computational pharmacophore model of A II, were used to evaluate structural parameters of the new compounds, in comparison to other known A II antagonists (e.g., DUP-753 and SK&F 108566). According to the modeling studies, the introduction of a (carboxyheteroaryl)methyl moiety at the 3-position of the pyrimidinone ring led to derivatives with increased potency. Methyl 2-[[4-butyl-2-methyl-6-oxo-5-[[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl ]- 4-yl]methyl]-1-(6H)-pyrimidinyl]methyl]-3-thiophenecarboxylate (3k, LR-B/081), one of the most potent compounds in the series (Ki = 1.4 nM), exhibited a marked antihypertensive activity on oral administration to conscious renal hypertensive rats, with long duration of action. It was selected for clinical evaluation in the treatment of hypertension in man.

Pharmacology of LR-B/081, a new highly potent, selective and orally active, nonpeptide angiotensin II AT1 receptor antagonist.

1. The pharmacological profile of LR-B/081, (methyl 2-[[4-butyl-2-methyl- 6-oxo-5-[[2'-(1H-tetrazol-5-yl)[1,1'-biphenyl]-4-yl]methyl]-1(6H)- pyrimidinyl]methyl]-3-thiophenecarboxylate), a novel antagonist at the angiotensin II (AII) AT1-receptor, was studied in vitro and in vivo. 2. In rabbit aortic strips incubated with LR-B/081 (1-1,000 nM), the concentration-response curve to AII was displaced to the right in a nonparallel fashion and the maximal contraction was progressively reduced, indicating that the compound is an insurmountable antagonist in this preparation (apparent pKB = 9.50 +/- 0.23). However, the interaction of LR-B/081 with AII receptors was found to be reversible, since the maximal response to AII was restored by coincubation with losartan, a surmountable AII AT1-antagonist. Contractions elicited by KCl or phenylephrine were not affected by 10 microM LR-B/081. 3. In rat isolated perfused kidney, LR-B/081 and losartan antagonized the AII-induced vasoconstriction [IC50 (95% confidence limits) = 17(13-24) and 39(32-54) nM, respectively]. The LR-B/081 antagonism was incompletely reversed by excess AII, while losartan was fully displaced. The IC50 values of LR-B/081 and losartan obtained against vasoconstriction induced by endothelin-1 and noradrenaline were two orders of magnitude higher. 4. In pithed rats, the intravenous administration of LR-B/081 (0.2-2 mumol kg-1) dose-dependently shifted to the right in a nonparallel fashion the dose-pressor response curve to AII. The maximal pressor response to AII was reduced by LR-B/081 in a dose-dependent fashion. The coadministration of losartan induced a progressive recovery of the maximal pressor response to All, indicating that in vivo the interaction of LR-B/081 with All receptors is reversible. LR-B/081 at 6 micromol kg-1, i.v. also did not affect the vasopressor response induced by noradrenaline in the pithed rat.5. In conscious normotensive rats, single oral administration of LR-B/081 at 6 micromol kg-1 markedly inhibited the All-induced pressor response; the inhibition lasted more than 24 h.6. In conscious renal hypertensive rats, intravenous LR-B/081 appeared as potent as losartan (ED40mmHg(95% confidence limits) = 0.50(0.36-0.70) and 0.86(0.57-1.3) micromol kg-1, respectively). A single intravenous(2 micromol kg-1) or oral (6 micromol kg-1) administration of LR-B/081 induced a marked fall in blood pressure which lasted for at least 12 h.7. In conscious spontaneously hypertensive rats, LR-B/081 at 20 micromol kg-1 , p.o., induced a marked and sustained fall in blood pressure. The duration of the antihypertensive effect was longer than 12 h.Heart rate was not modified by LR-B/081 treatment. Repeated oral administration of 17 micromol kg-1LR-B/081 for 16 days did not result in the development of tolerance.8 These results demonstrate that LR-B/081 is a potent, selective and orally active antagonist of All at the AT1-receptor subtype, which markedly lowers the blood-pressure in conscious renal and spontaneously hypertensive rats.

Effect of graded doses of PGE2 on pancreatic exocrine secretion of bicarbonate, chymotrypsin and cyclic nucleotides during i.v. infusion of secretin in man.

We have previously reported that PGE2 inhibits pancreatic enzyme secretion during Secretin-Caerulein infusion, but differing results have also been reported. In this study 10 tests were performed in 5 healthy volunteers as follows: each subject received secretin (GIH) 2 CU/Kg-h by continuous infusion for 2 hours and, several days later, Secretin at the same dose plus PGE2 (Upjohn) in step-wise doses (0.04-0.08-0.12 gamma/Kg min) increasing every thirty min form 30' to 120' min. Duodenal juice was collected in 10 min samples. The volume of each sample was recorded and bicarbonate, chymotrypsin, cAMP and cGMP contents were determined. Statistical evaluation was performed by Student's "t" test for paired data and the regression test. PGE2 significantly decreased chymotrypsin concentration under Secretin. Both cyclic AMP and GMP Secretin-induced secretions were significantly increased by the highest dose of PGE2. No correlation was found in the behaviour of bicarbonate, chymotrypsin and cyclic nucleotides, but it must be noted that our data concern duodenal contents and not pure pancreatic secretion.

Prevention of experimentally induced gastric damage with the tripeptide ZAMI-420, a new thromboxane synthesis inhibitor.

There is accumulating evidence that the presence of the imidazole ring is essential for the inhibition of the thromboxane synthetase activity of several compounds synthetized so far. Inhibition of arachidonic acid (AA) induced platelet aggregation was observed by us with a series of tripeptides in which the imidazole ring belongs to histidine, included in a proper aminoacid sequence. Among these compounds the N-acetyl-L-phenylalanyl-L-phenylalanyl-L-histidine methylester (ZAMI-420) was the most effective. The bioassay of the supernatant of an AA-added platelet-rich plasma (PRP) preparation, preincubated with increasing concentrations of ZAMI-420, showed a dose-related reduction in thromboxane-A2 (TXA2)-like activity, an increase of PG-like response and disappearance of the TXB2 peak in the radiochromatogram; RIA experiments led to the same results. ZAMI-420 does not influence cyclooxygenase activity as the AA-induced increase in O2-consumption by the microsomal fraction of bovine seminal vesicles was unaltered by this compound. Administered orally to the rat, ZAMI-420 was able to prevent gastric damage provoked by a variety of pharmacological agents, including ASA, 5HT and alcohol. The protective effect on experimentally-induced gastric damage is not mediated through the antisecretory properties of this compound but is more likely to be due to a cytoprotective mechanism based on blockade of TXA2 synthesis.

Pharmacokinetics of diltiazem and a new analogue, LR-A/113, in the conscious rat.

Pharmacokinetics and metabolism of diltiazem and a new analogue, LR-A/113, have been studied in the rat. Conscious rats, with the jugular vein cannulated, received the compounds by intravenous (3 mg/kg body weight) or oral (50 mg/kg body weight) route. Parent compounds and their N-demethyl and N-deacetyl metabolites were assayed at serial times in blood. Half-life of elimination of diltiazem was significantly shorter than that of LR-A/113, both after oral (37 +/- 9 vs 59 +/- 26 min) and intravenous (29 +/- 12 vs 57 +/- 16 min) administration. N-deacetyl-diltiazem concentrations after oral administration were higher than the parent compound and N-demethyldiltiazem; LR-A/113 blood concentrations were higher than those of its two metabolites. Metabolites were measurable only in traces after intravenous administration. Oral bioavailability was very low, 3.5% for diltiazem and 4.2% for LR-A/113. In conclusion, the substitution of a methyl by an isopropyl group appears to slow in vivo elimination of the analogue of diltiazem, LR-A/113.

[Artificial (parenteral and enteral) nutrition in postoperative rehabilitation]. / Nutrizione artificiale (parenterale ed enterale) nella riabilitazione post-chirurgica.

Post-surgical rehabilitation requires a full knowledge of the physiopathological basis and a great capacity to evaluate with specific tools, essential function and variations of digestive system. These problems have been underlined by the Authors specifically for gastric surgery in general, for movement factors of intestinal surgery and related nutritional implications for Crohn's disease, chronic intestinal insufficiency, enteric fistulas, severe exocrine pancreatic insufficiency, related to resective pancreatic surgery and for external pancreatic fistulas. The last words have been devoted to peri-operative parenteral nutrition.

The impact of discrete compartments of a multi-compartment collagen-GAG scaffold on overall construct biophysical properties.

Orthopedic interfaces such as the tendon-bone junction (TBJ) present unique challenges for biomaterials development. Here we describe a multi-compartment collagen-GAG scaffold fabricated via lyophilization that contains discrete mineralized (CGCaP) and non-mineralized (CG) regions joined by a continuous interface. Modifying CGCaP preparation approaches, we demonstrated scaffold variants of increasing mineral content (40 vs. 80wt% CaP). We report the impact of fabrication parameters on microstructure, composition, elastic modulus, and permeability of the entire multi-compartment scaffold as well as discrete mineralized and non-mineralized compartments. Notably, individual mineralized and non-mineralized compartments differentially impacted the global properties of the multi-compartment composite. Of particular interest for the development of mechanically-loaded multi-compartment composites, the elastic modulus and permeability of the entire construct were governed primarily by the non-mineralized and mineralized compartments, respectively. Based on these results we hypothesize spatial variations in scaffold structural, compositional, and mechanical properties may be an important design parameter in orthopedic interface repair.

Toxicological and pharmacological investigations of pinazepam (7-chloro-1-propargyl-5-phenyl-3H-1,4-benzodiazepin-2-one): a new psychotherapeutic agent.

The pharmacological and toxicological properties of 7-chloro-1-propargyl-5-phenyl-3H-1,4-benzodiazepin-2-one (pinazepam) were investigated and compared with those of diazepam. In mouse and rat acute toxicity, in rat motor coordination and in rat metrazol convulsion tests pinazepam was compared with oxazepam too. Pinazepam, which is characterized by the presence of a propargylic side chain, showed a lower toxicity, hypnotic activity and muscular-relaxant activity than diazepam. Pinazepam and diazepam showed, however, similar activity in reducing aggressive behaviour in mice, stimulating the exploratory behaviour in rats and in potentiating hexobarbital narcosis. No clear-cut differences were observed in the anticonvulsant properties of the two drugs when tested against metrazol, strychnine and electroshock induced seizures. Pinazepam differs from diazepam for its longer duration of action. The main metabolic product found in the urine of rats and dogs treated with pinazepam was oxazepam.

Pancreatic extracts are necessary for the absorption of elemental and polymeric enteral diets in severe pancreatic insufficiency.

Tube feeding nutrition, either elemental or polymeric, is increasingly used in patients with digestive problems. Pancreatic insufficiency is a widely accepted indication for the use of an elemental formula, which requires less residual digestive capacity. To confirm this assumption, we have compared the absorption of elemental and polymeric diets and the effect of exogenous pancreatic enzymes in a patient on long-term total enteral feeding after total pancreatectomy. Malabsorption of both formulas was observed without enzyme supplementation. A marked improvement of fat and nitrogen absorption was obtained when pancreatic enzymes were added to both enteral diets. It is concluded that pancreatic enzymes should always be added to liquid diets in pancreatic insufficiency. No clear advantage is to be anticipated by the use of elemental as compared with polymeric diets.

Medium-chain triglyceride absorption in patients with pancreatic insufficiency.

BACKGROUND: The role of medium-chain triglycerides (MCTs) in the management of patients with pancreatic insufficiency is controversial. The aim of the study was to evaluate the absorption of MCTs in the presence of pancreatic insufficiency and the effect of pancreatic extracts on MCT absorption so as to clarify whether the replacement of usual dietary fats with MCTs is cost-effective. METHODS: Six patients with severe pancreatic steatorrhea were for 5 days fed a low-fat diet to which butter (long-chain triglycerides (LCTs)) or MCT oil was added, with and without pancreatic extracts, in a crossover design. RESULTS: Fecal weight and nitrogen losses were the same during MCT and LCT intake. Steatorrhea was substantial during both periods but was significantly lower during MCT than LCT intake. Fecal weight and nitrogen and fat losses were reduced by pancreatic extracts in both diets. Steatorrhea was the same when MCTs and LCTs were consumed together with pancreatic extracts. CONCLUSIONS: MCTs are absorbed better than LCTs in the presence of pancreatic insufficiency but require pancreatic extracts for optimal absorption. No advantage is to be expected from replacing usual dietary fats with MCTs if pancreatic supplements are used.

Fecal fat measurement in the presence of long- and medium-chain triglycerides and fatty acids. Comparison of three methods.

BACKGROUND: It has been suggested that some of the limitations of the Van de Kamer method for fecal fat measurement could be overcome with the Jeejeebhoy method or the near-infrared reflectance assay. METHODS: To test this hypothesis, a fecal fat test was carried out with the three methods, adding butter or MCT oil to the diet of four steatorrhoic patients. An in vitro recovery study of long- and medium-chain triglycerides was also performed. RESULTS: The Jeejeebhoy method measured long- and medium-chain fats more accurately than the Van de Kamer method. It found consistently higher steatorrhea values. Mean results of the near-infrared reflectance analysis resembled those of the Van de Kamer method, but with wide discordance of individual data. CONCLUSION: The Jeejeebhoy method is more accurate than the Van de Kamer method for fecal fat measurement. The difference may be clinically relevant when most fecal fatty acids derive from medium-chain triglycerides. Near-infrared reflectance may be a viable proposition only when a greater degree of approximation is acceptable.

Gastric emptying and dyspeptic symptoms in patients with gastroesophageal reflux.

OBJECTIVES: To clarify 1) whether gastric emptying of a mixed meal is delayed in patients with gastroesophageal reflux and 2) the relationship between dyspeptic symptoms and delayed gastric emptying in refluxers. METHODS: Gastric emptying of a solid meal was studied by ultrasound in 25 patients with pathological esophageal acid exposure. Gastric emptying was then assessed in relation to upper digestive endoscopy, esophageal manometry, 24-h pH monitoring and quantification of symptoms of reflux- and dysmotility-like dyspepsia. RESULTS: Fifteen of 25 refluxers had esophagitis, and 15 were "dyspeptic". Refluxers exhibited a significant delay in gastric emptying compared with controls [307.6 (21.0) vs. 209 (10.4) min, p < 0.001). Patients with delayed emptying had low LES pressure [11.9 (2.1) vs. 18.6 (2.1) mm Hg, p < 0.05]. There was no correlation between delayed emptying and either pH monitoring or presence of esophagitis. There were no differences in any of the pH monitoring parameters between refluxers with and without coexisting dysmotility-like symptoms. CONCLUSIONS: Gastric emptying of a solid meal is markedly delayed in patients with gastroesophageal reflux. However, no direct causal link was found between delayed emptying and reflux. Our data suggest the presence of a motility disorder in gastroesophageal reflux which is not confined to the esophagogastric junction.

Pharmacological properties of the anti-inflammatory agent pyridyl-biphenylyl-acetamide (diphenpyramide).

Pyridyl-biphenylyl-acetamide (diphenpyramide, Z-876) is a new bisphenylalcanoic derivative with marked anti-inflammatory, analgesic, antipyretic and uricosuric properties. It is more active than phenylbutazone in the adjuvant polyarthritis in the rat when given prophylactically or therapeutically. It is thrice as active as phenylbutazone and ten times as active as acetylsalicylic acid (ASA) on the carrageenin-induced edema of the hind-paw. Diphenpyramide is characterized by low acute toxicity and by weak ulcerogenic activity. On the carrageenin-induced edema the therapeutic index of diphenpyramide is 30 times higher than that of indometacin and the ratio between the ED50 and the UD50 (ulcerogenic dose in 50% of the treated rats) is 39 times higher than that of ASA.

Gastric emptying of solid meals in achalasic patients after successful pneumatic dilatation of the cardia.

Gastric emptying of a solid meal was measured by ultrasound scanning in 16 achalasic patients following successful pneumatic dilatation of the lower esophageal sphincter. The data were compared with those of a control group of 15 healthy subjects. Fasting and maximal postcibal antral sections were very similar in the two groups. On the contrary, the time interval before maximal antral dilatation, and the time necessary for the emptying of half or of the whole meal were significantly longer in the achalasic patients than in the controls. Half of the achalasic patients had longer emptying times than the upper normal limit. The percentage of the meal retained in the antrum at each hourly interval was significantly higher in the achalasic group. The finding of a high prevalence of gastric emptying disturbances suggests that the functional derangement in achalasia is not limited to the esophagus.

Near infrared spectrometry for faecal fat measurement: comparison with conventional gravimetric and titrimetric methods.

This investigation was aimed at comparing a new method for measuring faecal fat excretion, carried out with a semi-automated instrument by using near infrared analysis (NIRA), with the traditional titrimetric (Van de Kamer) and gravimetric (Sobel) methods. Near infrared analysis faecal fat was assayed on the three day stool collection from 118 patients (68 chronic pancreatitis, 19 organic diseases of the gastrointestinal tract, 19 alcoholic liver disease, 12 functional gastrointestinal disorders). A strict linear correlation was found between NIRA and both the titrimetric (r = 0.928, p less than 0.0001) and the gravimetric (r = 0.971, p less than 0.0001) methods. On homogenised faeces, a mean coefficient of variation of 2.1 (SD 1.71)% was found. Before homogenisation (where a mean coefficient of variation of 7% was found) accurate results were obtained when the mean of five measurements was considered. In conclusion, the assay of faecal fat excretion by the near infrared reflessometry appears a simple, rapid and reliable method for measuring steatorrhoea.

Fecal fat concentration in the screening of steatorrhea.

We studied if the fecal fat concentration as measured by the near infrared reflectance analysis in a spot sample is an acceptable screening test for malabsorption. This measurement was compared with the more complex fat balance in 120 patients with a suspected malabsorption [53 with chronic pancreatic disorders (CP), 67 with other digestive disorders (nCP)]. The fecal fat concentration proved to be well correlated with steatorrhea in CP (r = 0.86) but not in nCP (r = 0.35). A fat concentration of 9 g% had a sensitivity and a specificity for steatorrhea of 88.8% and of 97.1% in CP, but only of 53.8% and of 94.4% respectively in nCP. The fecal fat concentration was significantly higher in CP than in nCP, even considering patients with steatorrhea only; however, the overlap between the two groups was too high to suggest a clinical usefulness of this test in the differential diagnosis of steatorrheas. It is concluded that the fat concentration in a small sample, easily obtained also in outpatients, is useful in the selection of patients with chronic pancreatitis to submit to a proper fat balance study.

Omeprazole causes delay in gastric emptying of digestible meals.

We have studied gastric emptying of a solid, realistic meal (800 cal, 15% protein, 45% fat, 40% carbohydrate) in 21 healthy subjects twice, with and without a four-day pretreatment with 40 mg omeprazole. The last dose of the drug was taken 24 hr before the test, to avoid hypothetical nonsecretory side effects of the drug . Gastric emptying was measured by ultrasound of antral diameters. The results show that basal and maximal postprandial antral cross-sectional areas were the same during the two tests. A greater residual distention of the antrum was present throughout the study after the omeprazole treatment, the difference being significant at time 120 and 240. Omeprazole induced a highly significant delay in gastric emptying [control 199.6 (12.6) vs omeprazole 230.9 (12.7) min, mean (1 SEM); P<0.003]. The delay was not due to a prolonged lag phase, but rather to an effect on the slope of the emptying curve. This study shows that in normal subjects omeprazole delays gastric emptying of a digestible solid meal.